Primary objectives of the project are two-fold: 1) To Study the Role of Intestinal Mucosa in the Development of Irreversible Shock - Most investigators report that there is little intestinal involvement in clinical forms of shock which is in sharp contrast to the severe intestinal damage found in the dog with hemorrhagic shock produced by the reservoir method. We intend to compare hemorrhagic shock (reservoir method) with the single hemorrhage method which produces lesser intestinal involvement. Lightly anesthetized dogs will be subjected to hemorrhagic shock using the single hemorrhage method. Arterial and venous pressures, blood gases and lactate levels will be maintained. Plasma lysosomal enzyme (acid phosphatase and cathepsin) and ornithine carbamyltransferase (liver specific) levels will be determined and the major source of the first two enzymes assessed by histological examination of splanchnic tissues. These results will be compared with those of the reservoir method previously done. 2) The Protective Effects of Glucocorticoids in the Single Hemorrhage Method of Hemorrhagic Shock - Animals will be treated in a manner similar to that described above with the exception that they will receive a large dose (30 mm/kg) of methylprednisolone before the hemorrhage. These results when compared to those previously obtained with the reservoir method will add to our understanding of the protective effects of glucocorticoids.